To make sense of our unpredictable world, humans use sensory information streaming through billions of peripheral neurons. Uncertainty and ambiguity plague each sensory stream, yet remarkably our perception of the world is seamless, robust and often optimal in the sense of minimising perceptual variability. Moreover, humans have a remarkable capacity for dexterous manipulation. Initiation of precise motor actions under uncertainty requires awareness of not only the statistics of our environment but also the reliability of our sensory and motor apparatus. What happens when our sensory and motor systems are disrupted? Upper-limb amputees tted with a state-of-the-art prostheses must learn to both control and make sense of their robotic replacement limb. Tactile feedback is not a standard feature of these open-loop limbs, fundamentally limiting the degree of rehabilitation. This thesis introduces a modular closed-loop upper-limb prosthesis, a modified Touch Bionics ilimb hand with a custom-built linear vibrotactile feedback array. To understand the utility of the feedback system in the presence of multisensory and sensorimotor influences, three fundamental open questions were addressed: (i) What are the mechanisms by which subjects compute sensory uncertainty? (ii) Do subjects integrate an artificial modality with visual feedback as a function of sensory uncertainty? (iii) What are the influences of open-loop and closed-loop uncertainty on prosthesis control? To optimally handle uncertainty in the environment people must acquire estimates of the mean and uncertainty of sensory cues over time. A novel visual tracking experiment was developed in order to explore the processes by which people acquire these statistical estimators. Subjects were required to simultaneously report their evolving estimate of the mean and uncertainty of visual stimuli over time. This revealed that subjects could accumulate noisy evidence over the course of a trial to form an optimal continuous estimate of the mean, hindered only by natural kinematic constraints. Although subjects had explicit access to a measure of their continuous objective uncertainty, acquired from sensory information available within a trial, this was limited by a conservative margin for error. In the Bayesian framework, sensory evidence (from multiple sensory cues) and prior beliefs (knowledge of the statistics of sensory cues) are combined to form a posterior estimate of the state of the world. Multiple studies have revealed that humans behave as optimal Bayesian observers when making binary decisions in forced-choice tasks. In this thesis these results were extended to a continuous spatial localisation task. Subjects could rapidly accumulate evidence presented via vibrotactile feedback (an artificial modality ), and integrate it with visual feedback. The weight attributed to each sensory modality was chosen so as to minimise the overall objective uncertainty. Since subjects were able to combine multiple sources of sensory information with respect to their sensory uncertainties, it was hypothesised that vibrotactile feedback would benefit prosthesis wearers in the presence of either sensory or motor uncertainty. The closed-loop prosthesis served as a novel manipulandum to examine the role of feed-forward and feed-back mechanisms for prosthesis control, known to be required for successful object manipulation in healthy humans. Subjects formed economical grasps in idealised (noise-free) conditions and this was maintained even when visual, tactile and both sources of feedback were removed. However, when uncertainty was introduced into the hand controller, performance degraded significantly in the absence of visual or tactile feedback. These results reveal the complementary nature of feed-forward and feed-back processes in simulated prosthesis wearers, and highlight the importance of tactile feedback for control of a prosthesis.

Development of an Open Source Prosthetic Hand Platform Scott Garrett In the field of upper extremity prosthetic devices, advancements in technology drive the design of products which are becoming capable of restoring the lost functions of the native hand. While several dexterous devices have been developed to serve this purpose, they remain prohibitively expensive and thus are not a viable option for many upper extremity amputees. To address this problem a prosthetic hand platform was developed utilizing the open source Arduino microcontroller and off-the-shelf electrical components. Using these resources, a novel finger actuation mechanism was developed to show how a prosthetic hand platform could be developed which is capable of individual finger actuation, multiple actuation modes, sensing of forces at the individual fingers, providing force feedback to the user, and control of finger actuation through a variety of control inputs. After going through several iterations of hand’s mechanical components, electronics, and firmware a final prototype was built to showcase the possible capabilities of the open source prosthetic hand platform. This prototype consisted of several groups of subcomponents including an auto-flexing / extending finger design, a modular palm/ servo attachment base, and a wrist section which housed the hand’s electronic components, power supplies, force feedback system. The open source prosthetic hand platform was then verified using a series of tests to quantify several performance characteristics of the final prototype. Battery life and grip strength during continuous use were evaluated and demonstrated that the hand could provide consistent grip force during up two hours of initial continuous use. Also, the grip performance of the hand was assessed through the grasping of spherical objects with varying surface textures, diameter, and weight. Furthermore the hand was tested in various “real life” applications including manipulating and sorting small objects, opening doors, grasping moderately heavy objects such as water bottles, and sensitive objects such as an egg. Lastly, the platform was connected to a myoelectric input circuit to demonstrate compatibility with advanced electro-physical inputs. These tests demonstrated that the platform was capable of performing some of the dexterous tasks performed by prohibitively expensive available robotic upper extremity prosthetic devices. Further developments could be made to the open source prosthetic hand platform including enhancements to the platform’s finger force sensing and feedback mechanisms, consolidation of the electronics, refinement of the auto-flexing / extending fingers, and integration with a silicone covering and patients residual limb socket. These future iterations of this platform could help provide a dexterous prosthetic hand platform at lower cost to a wider patient base.

Losing a hand is a highly traumatic experience affecting both the physical life and mental wellbeing of a person. It is therefore vital to provide a prosthetic hand with similar functionality to the hand lost. The human hand is a very delicate and complex part of the body used every day in a wide range of tasks from performing heavier works to smaller gestures. Due to all factors playing arole in how amputees live their lives, recreating a human hand is a very demanding and challenging task. As many as 30% of amputees experience depression and/or anxiety as a result of not having the same capabilities and opportunities as before the amputation. Amputation may be carried out both due to sudden accidents and as a result of congenital defiances and vascular illnesses. Since advanced prosthetic hands often come in at a price too high to reach a large part of the amputee consumer base, the case is often that only the richest amputees are able to afford electric prosthetic devices, and are thus often limited to simpler, body-powered alternatives. These alternatives are often found to be lacking in features and resemblance when comparing to the more technologically advanced electric prosthetics. A set of product development tools and methods were selected for the development process to ensure an organized approach for the project. The project was concluded with a finished and fully-manufacturable prosthetic hand with some advantages compared to the current market products. The hand developed in the project, named OYMotion hand 1.0 proved to have a number of advantages over competing products in selected functional areas such as force, finger speed and weight. The final market price of the product could not be estimated due to the fact that there are too many unknown factors involved to determine a final market price on the hand. The production cost is, however estimated to be significantly lower than the measured competing prosthetic hands. A deepened understanding about prosthetic hand design and development was obtained by studying the market, EMG, machine learning applications, hardware, gears, finger mechanisms,and materials.  By balancing concepts between cost, functionality and aesthetics, a structured reasoning couldbe used to prioritize certain aspects of the developing of the hand.The completed hand fulfills the required specifications and functions after undergoing anumber of analyses conducted in order verify material strength and mechanism functionality.Further grip strength analyses and calculations were excluded from the study due to the limitedavailable time given.

Práce předkládá metody a výsledky návrhu, výroby a výzkumu pětiprsté protézy ruky. Inspirace jdoucí z přírody a z toho vyvozený princip použitého mechanizmu je uveden. Základní koncept řídícího schéma založeného na procesingu a ohodnocení EMG je navrhnut a implementován. Části senzorického systému protézy jsou navrhnuty a zahrnuty do rídícího algoritmu a shématu. Velké množství inovací a návrhů pro budoucí práce a výzkum jsou prezentovány, stejně tak komplexní analýza a diskuse dosažených a možných budoucích výsledků.

Prosthetic development recently has focused mainly on myoelectrically controlled electric hands despite a majority of upper extremity amputees actively choosing body powered devices. Myoelectric hands utilize a small electric pulse generated in muscles when flexing as a signal to the hand to close. Finger flexion in these devices is controlled by electromechanical servos, requiring no strength input from the user. Body powered devices use a cable attached to a shoulder harness which causes mechanical closure of the device via tension placed on a control cable by a shoulder shrug motion or arm extension. Outfitting of active duty service personnel has recently tended to follow the electronic hands which have fragile electronics, have a poor response to user input, and are not fit for harsh outdoor environments. This report will detail the current development of a re-design of a custom left hand prosthesis for an active duty Navy SEAL and the transition from electronic controls to full body power function.

Limb loss has severe physical and psychological effects on individuals with upper limb amputations. Higher rates of prosthetic device abandonment has contributed to a need for prosthetic hands that are functional and comfortable for the user. Prosthetic hands have been abandoned for many reasons including weight, size, limited functionality, training time, and discomfort. An optimal prosthetic hand considers both neural control and sensory feedback. Neural control of the prosthetic is crucial to obtain accuracy and desirable functions. Popular methods of sensory feedback such as visual feedback are mentally exhausting and require constant focus from the user. Control and feedback of prosthetic devices differs based on the type of prosthetic. Passive, myoelectric, body-powered, electrocorticographic, adaptive, and sonomyographic prosthetic hand devices focus on a variety of hand movements and each utilizes different methods of control. It is also important to consider the biomaterials of prosthetic hands to enhance comfort and ease-of-use. Mechanical and AM-ULA testing ensure prosthetic hands can perform necessary movements for the user. To develop an ideal prosthetic hand, control and feedback must be considered along with comfort and functionality of the device.

No description available.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-10-09T12:55:34Z No. of bitstreams: 2 Dissertação - Guilherme Ferreira Neto - 2017.pdf: 19155056 bytes, checksum: 9c8085aa41dd3dccbbaf9ad4c9c5fbe3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-10-09T12:55:56Z (GMT) No. of bitstreams: 2 Dissertação - Guilherme Ferreira Neto - 2017.pdf: 19155056 bytes, checksum: 9c8085aa41dd3dccbbaf9ad4c9c5fbe3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-10-09T12:55:56Z (GMT). No. of bitstreams: 2 Dissertação - Guilherme Ferreira Neto - 2017.pdf: 19155056 bytes, checksum: 9c8085aa41dd3dccbbaf9ad4c9c5fbe3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-04-03 / Among the parts of the body, the hand is one of the most important for the humans because of their versatility and ability to manipulate objects. Many people do not have this member, either congenital malformation or necessity of amputation which make their day by day hardy. The existing comercial prosthesis have high costs making it inusual for a signifcative part of patients, on the other hand, there are at Internet communities to develop more accessible hand prostheses, for manufacturing by 3D printing but, It generally use unefficient activation methods. The target of this study is to develop the mechanical structure of a prosthesis hand with individual drive for each fingers, which can be make by using 3D printing, making it the most accessible price and the most efficient prosthesis when compared with current ones. For this, a mathematical model that describes the motion of the robotic finger will be determined. This finger has as actuator, DC motors, coupled to gears which in by their self are coupled in arms. The results will be checked by comparing the movements performed bettewen a prototype of the prosthesis and the determined mathematical model. It is expected that the prosthesis proposed by this research is the structural base for future stages of the development of a full prosthesis activated by voice command. / Dentre os membros motores, a mão tem grande importância para os seres humanos devido à sua versatilidade e capacidade para manipular objetos. Muitas pessoas não têm este membro, seja por má formação ou por amputação, o que dificulta na execução das atividades cotidianas. As próteses comerciais existentes têm custo elevado inviabilizando a utilização para a maioria das pessoas que dela necessita, por outro lado, existem comunidades na internet que desenvolvem próteses de mão acessíveis, via processo de fabricação por manufatura aditiva, porém, geralmente com métodos de acionamento pouco eficientes e pouco ergonômicas. Este estudo apresenta o desenvolvimento da estrutura mecânica de uma prótese de mão com acionamento individual dos dedos. Para isso, é desenvolvido o modelo matemático que descreve o movimento do dedo robótico que tem como acionadores, motores de corrente contínua, acoplados a engrenagens que por sua vez estão conectadas a braços de movimento. É realizado um estudo cinemático do movimento dos dedos, além de simulação computacional para a estrutura mecânica proposta. Também foi construído um protótipo virtual parametrizado para checar a viabilidade de execução da mecânica proposta. A prótese proposta por esta pesquisa será a base estrutural para etapas do desenvolvimento de uma prótese acionada por comando de voz.

<p>From idea generation to conceptualization and development of products and technologies is a non-linear and iterative process. The work in this thesis follows a process that initiates with the review of existing technologies and products, examining their unique value proposition in the context of the specific applications for which they are designed. Next, the unmet needs of novel or emerging applications are identified that require new product or technologies. Once these user needs and product requirements are identified, the specific functions to be addressed by the product are specified. The subsequent process of design of products and technologies to meet these functions is enabled by engineering tools such as three-dimensional modelling, physics-based simulations, and manufacturing of a minimum viable prototype. In these steps, un-biased decisions have to be taken using weighted decision matrices to cater to the design requirements. Finally, the minimum viable prototype is tested to demonstrate the principal functionalities. The results obtained from the testing process identify the potential future improvements in the next generations of the prototype that would subsequently inform the final design of product. This thesis adopted this methodology to initiate the design two product-prototypes: i) an image-recognition-integrated service (IRIS) robotic hand for children and ii) cascaded multi-core vapor chamber (CMVC) for improving performance of next-generation computing systems. Minimum viable product-prototypes were manufactured to demonstrate the principal functionalities, followed by clear identification of future potential improvements. Tests of the prosthetic hand indicate that the image-recognition based feedback can successfully drive the actuators to perform the intended grasping motions. Experimental testing with the multi-core vapor chamber demonstrates successful performance of the prototype, which offers notable reduction in temperatures relative to the existing benchmark solid copper spreader. </p>